RU2231844C2 - Method of hydraulic protection of high-voltage pedestal insulators - Google Patents

Abstract

FIELD: electrical engineering.

SUBSTANCE: method includes application of low-viscosity silicon-organic composition that contains dimethylsiloxane raw rubber, aluminum hydroxide and catalyst in two stages. Sublayer from solution is applied with subsequent drying and then basic composition is deposited. In the capacity of basic composition there is utilized mixture of dimethylsiloxane raw rubber CKHT, brand A (parts by mass), silica powder A-175 (4-5 parts by mass), zinc oxide (4-6 parts by mass), aluminum hydroxide (80-100 parts by mass) and catalyst (3-26 parts by mass) and 50% solution of basic composition in white spirit with addition of 50% solution of catalyst in white spirit as sublayer. In specific case concrete interlayer of insulator is heated by industrial fan to temperature 105-110 C in the course of time established from mathematical expression prior to application of sublayer.

EFFECT: preparation of reliable sealing coat on surface of insulator parts made of various materials.

2 cl, 1 dwg, 3 tbl

Description

The invention relates to electrical engineering, and in particular to methods of hydroprotection of high voltage support insulators.

A known method of manufacturing high-voltage insulators, according to which a single-layer siloxane composition is applied to the surface of the insulator at room temperature. It is obtained by mixing polydimethylsiloxane, an aluminum hydroxide filler, and a curing catalyst. When interacting with atmospheric moisture, the composition cures, forming a coating on the surface of the insulator [1].

The known method has the following disadvantages:

- the proposed formulation of the composition is intended for applying to the surface of a glass rod located inside a ceramic insulator, and cannot be used for applying simultaneously to the surface of dissimilar materials, as in the design of a high-voltage support insulator - ceramic, concrete, metal;

- does not eliminate the presence of moisture in concrete and joints and, thus, the reason for the appearance of cracks and delamination of the sealing coating is preserved;

- does not take into account the influence of the environment on the quality of sealing (sealing is carried out only at room temperature) and thus exclude the sealing process directly at the places of operation of the equipment.

Among high-voltage insulators a significant place is occupied by ceramic insulators for voltage over 1000 V [2], designed to protect against lightning and switching overvoltages.

The drawing shows the design of such an insulator, the method of waterproofing which is closest in technical essence and the desired result claimed.

The design of the high-voltage supporting insulator consists of a ceramic product 1, metal reinforcement 2 and a concrete layer 3, which serves to connect the ceramic and metal parts to each other. Thus, the design feature of the supporting insulators is the existence of joints 4 and 5 between different materials, where moisture penetrates. In addition, the concrete layer, being porous, itself absorbs a certain amount of moisture, which at low temperatures can cause it to crack and, ultimately, the failure of the insulator. Therefore, the joints of the parts and the concrete layer of the insulator must be sealed.

A known method of sealing the joints of parts of the supporting insulator by coating them with an even layer of compensating grease (varnish BT-99, varnish BT-577) [2].

However, this method is not reliable, since under the influence of atmospheric conditions, high voltage, causing the insulator to heat up, light-gap and ultraviolet exposure, such a coating quickly crackes and peels off. Having low elasticity, the varnish film is able to quickly break down when coating the joints of materials with different temperature expansion coefficients, and due to the thin coating layer, the process of oxidation and aging of this film occurs quite quickly. Varnish coatings are usually flammable.

In addition, the method does not eliminate moisture in concrete and on the walls of the insulator, which contributes to its breakdown.

The objective of the present invention is to provide a new method of waterproofing high voltage support insulators, as a result of which receive a reliable waterproof coating of its parts.

The problem is solved by applying the method of hydroprotection of high-voltage supporting insulators by coating the parts of the insulator and the joints of these parts with an insulating coating, according to which according to the invention the insulating coating is applied in two stages, first a subcoat of the solution is applied to the protected surface, it is dried and then the main coating is applied to the subcoat , which use a composition consisting of 100 parts by weight dimethylsiloxane rubber SKTN grade A (GOST 13835-73, TU 38403351-80), (4-7) wt.h. Aerosil A-175 (GOST 14922-77), (4-6) parts by weight zinc oxide, (80-100) parts by weight aluminum hydroxide, (3-6) parts by weight mixtures of tin dibutyl dilaurate with tetraethoxysilane as a catalyst (TU 6-02-805-78) during curing of the main coating, and as a solution for the formation of a sublayer, use a 50% solution of the main coating in white spirit with the addition of a 50% catalyst solution in white spirit .

Before applying the sublayer, the concrete insulator layer can be heated to a temperature of 105-110 ° C for a time determined from the dependence

τ = 3.26 · 10 ⁶ (δ $\genfrac{}{}{0ex}{}{\text{2}}{\text{c}}$ / d _c ) [(105-t _okr. ) / (2t _f -105-t _okr. ),

wherein _n and δ _n d - diameter and thickness of the concrete layer, respectively;

t _f , t _ocp. - the temperature of the hair dryer and the environment, respectively.

The coating made according to the claimed method and with the specified ratio of the components has a high hydrophobicity: 30-50 years, great elasticity due to the presence of dimethylsiloxane rubber in the composition.

Operating temperature range: -50 ° С - + 150 ° С, which allows to withstand winter cooling and heating of the insulator under high voltage. The coating material made by the specified method does not support combustion.

The possible warming up of the concrete layer of the insulator before applying the sublayer to a temperature of 105-110 ° C for a time determined from the above dependence ensures the elimination of moisture in the concrete and on the walls of the insulator, which is especially important during the repair of the insulator.

Thus, the support insulator made by the claimed method has high reliability.

A comparative analysis of the proposed method and the prototype reveals the distinctive features of the proposed method in comparison with the closest analogue, which allows us to conclude that the proposed solution meets the criterion of "novelty."

The presence of distinctive features makes it possible to obtain a positive effect, expressed in the creation of a new method of waterproofing of high voltage support insulators, as a result of which a reliable waterproof coating of its parts is obtained.

Since when examining the subject of the invention in patent and scientific literature, no solutions were found containing the features of the claimed invention other than the prototype, it should be concluded that the claimed invention meets the criterion of "inventive step".

The use of the claimed invention in electrical engineering ensures that it meets the criterion of "industrial applicability".

The sequence of operations in the practice of the proposed method of hydroprotection of high voltage support insulators is as follows.

First, the protected surface is dehydrated and degreased with white spirit and acetone, followed by exposure at a temperature of 120 ° C (using an industrial hair dryer) for 8-10 minutes. After that, a sublayer is applied to the surface to be protected. After the solvent has evaporated (after 5-10 minutes), the sublayer is heated at a temperature of 60-80 ° C for 30 minutes and the main sealing composition with a catalyst is applied to the prepared surface with a sublayer.

The composition cures naturally, depending on the ambient temperature, from 2 hours (at + 50 ° C) to 48 hours (at -50 ° C).

The protected surface before applying the undercoat, especially during repairs after cleaning from paint, can be heated with an industrial hairdryer to remove moisture from the concrete layer and joints with the horizontal direction of the heat flow through the metal reinforcement 2 (see drawing). Warm-up time is set in accordance with the dependence

τ = 3.26 · 10 ⁶ (δ $\genfrac{}{}{0ex}{}{\text{2}}{\text{c}}$ / d _c ) [(105-t _okr. ) / (2t _f -105-t _okr. ),

wherein _n and δ _n d - diameter and thickness of the concrete layer, respectively;

t _f , t _okr. - the temperature of the hair dryer and the environment, respectively.

Depending on the size of the dryer nozzle, the entire layer of the insulator is gradually heated.

Example 1. According to the described technology, a composition of the following composition is made (table. 1)

After curing, the compositions were tested in a number of ways. The results are shown in table 2

As can be seen from the data presented, a decrease in the content of components below the established limits significantly reduces the physical, mechanical and operational performance. An increase in the content of components above the upper limit does not lead to a significant increase in the performance, while elongation to rupture and dielectric strength drop.

Example 2. The insulator is heated with an industrial hairdryer (hair dryer temperature t _f = 400 ° C) at an ambient temperature of -10 ° C, -5 ° C, 0 ° C, 10 ° C, 20 ° C. The time to reach a temperature of 105 ° C on the surface of the concrete interlayer was fixed at the point farthest from the hairdryer surface (the junction of the concrete and porcelain surfaces). The experimentally established and estimated time were compared (Table 3) (δ _c = 15.10 ^-3 m, d _c = 180 · 10 ^-3 m).

Example 3. An insulator with geometric dimensions similar to example 2, we heat an industrial hairdryer at a hairdryer temperature of 150 ° C, 200 ° C, 250 ° C, 300 ° C, 350 ° C and an ambient temperature of 20 ° C. The time to reach a temperature of 105 ° C on the surface of the concrete interlayer was recorded and compared with the calculated one (Table 4)

Thus, the presented dependence is suitable for practical calculations.

Example 4. An insulator coated with waterproofing insulation was tested for peeling of the coating from the surface at various time intervals of 5, 10, 14, 20, 30 days. In all cases, a gap in insulation is observed in the material. Peeling from the parts of the insulator, as well as peeling of the waterproofing is not observed.

SOURCES OF INFORMATION

1. Application ЕВП No. 0123487, MKI N 01 B 19/04, 17/50, 3/46, publ. 1984 year

2. GOST 9984-85E “Ceramic support insulators, voltage above 1000 V” (prototype).

Claims (2)

1. The method of hydroprotection of high-voltage supporting insulators by coating the insulator parts and the joints of these parts with an insulating coating, characterized in that the insulating coating is applied in two stages: first, a subcoat of the solution is applied to the surface to be protected, it is dried and then the main coating is applied, as which use a composition consisting of 100 parts by weight SKTN dimethylsiloxane rubber grade A; 4 ÷ 7 parts by weight Aerosil A-175; 4 ÷ 6 parts by weight zinc oxide; 80 ÷ 100 parts by weight aluminum hydroxide and 3 ÷ 6 parts by weight mixtures of tin dibutyl dilaurate with tetraethoxysilane, as a catalyst during the curing of the base coat, and a solution of the formation of a sublayer is used as a solution of a 50% white coating in white spirit with the addition of a 50% solution of catalyst in white spirit. 2. The method according to claim 1, characterized in that before applying the sublayer, the concrete layer of the insulator is heated with an industrial hairdryer to a temperature of 105 ÷ 110 ° C for a time determined from the dependence τ = 3.26 · 10 ⁶ (δ $\genfrac{}{}{0ex}{}{\text{2}}{\text{c}}$ / d _c ) [(105-t _okp ) / (2t _f -105-t _okr )], wherein _n and δ _n d - diameter and thickness of the concrete layer, respectively; t _f , t _okr - the temperature of the dryer and the environment, respectively.